Successfully Retreading Wide Base Tires
During 2011, at many of the tradeshows we attended we would often get asked about the use and performance of wide base tires. Now, fast forward to 2013 and the Mid-American Trucking Show where we had a couple of wide base retreaded tires on display. The questions were still about the use of wide base tires but now there were more questions about the successful retreading of these tires.
We spoke to a couple of our members, a large retreader of wide base tires and a large trucking company that uses a high percentage of wide base tires in their operations. We wanted to get their thoughts on how retreaders can successfully retread these tires and how fleets are using the tires to their advantage.
Successful Retreading of Wide Base Tires
Ed Steck, Director of Franchise Business Services for Michelin Retread Technologies, described the three keys for successful wide base retreading: 1) There are real differences in the retread process compared to classic tire sizes, 2) All prescribed equipment and process differences must be used and followed, and 3) There aren’t any shortcuts and the process shouldn’t be rushed.
Let’s take a look at each stage the retreading process and how it differs for wide base tires:
Initial Inspection: First, retreaders need to ensure their lifting apparatus is capable of handling the casing width of the wide base tires. Second, their electronic liner inspection probe should have a minimum width of 12.1 inches. Lastly, the rotation speed of the inspection equipment should be reduced and the number of rotations increased to ensure a complete inspection of the casing.
Buffing: Here, retreaders need an expandable rim width of 14.5 inches and a minimum inflation pressure of 18 to 22 PSI before buffing is started. The buff radius should be 67 inches plus/minus 2 inches and a 67 inch buffing template is available from TRIB Member Tech International.
After Buff Inspection: If circumferential cracks or splits remain in one or both shoulders of the tire in the vicinity of the outside tread groove, the crack or split should be probed. If the probing penetrates into steel or feels soft/loose material, the casing should be rejected. This should not be confused with a 360 degree product interface line that sometimes is visible after buff. If this line is visible, it should be probed and if found to be loose material, reject the casing. If it is tight, continue the retread process.
Laser Shearopgraphy: For retreaders using laser shearography inspection, they will need to adjust and/or modify the process to ensure complete imaging from shoulder to shoulder, per the equipment manufacturer’s specifications. Additionally, it’s important to make sure the correct vacuum level is applied during shearography.
Building: As with buffing, an expandable rim width of 14.5 inches is required for building. Also, tread table rollers should be completely cleaned before each build series and tread building should not begin until tire pressure has reached the target inflation pressures in the expandable rim as defined by the retread process manufacturer. For cushion to casing extruded bonding gum application, the recommended minimum inflation pressure is 0.8 bar or 12 psi. Lastly, bonding gum thickness should not exceed 1.5 mm (2/32 inch) in the crown and 2.5 mm (3/32 inch) in the shoulders.
Enveloping, Curing and Final Inspection: It’s important that supplier recommended products and specifications from the process manufacturer are closely followed during these steps to ensure a successful retread.
Steck mentioned one final thought in ensuring success for the retreading of wide base tires, "The low volume of wide base tires retreaders see currently can be a challenge for developing operator efficiency, so it’s critical that operators understand and follow the published processes.”
A Fleet’s Perspective on Wide Base Tires
Alexander Conlan, Tire Department Manager for Prime Inc. has seen the wide base tire debate from both sides, having sold tires into Prime and then joining them to manage their tire programs. Headquartered in Springfield, Missouri, Prime Inc. is North America's most successful refrigerated, flatbed, tanker and logistics trucking company.
Prime started their switch to wide base tires in late 2009. They focused initially on their trucks for weight and fuel savings and after continued fuel testing starting using the tires on their trailers. Currently, Prime has wide base tires on all 5,000 of their trucks, on 50% of their refrigerated trailers, and 60% of their tanker trailers. Their plan is to have wide base tires on 100% of their trailers (except for spread-axle) as they move through the trade cycle. Retreading has always been an important part of Prime’s tire program, including with wide base tires. "We’re a green-focused company and retreading makes sense for so many reasons, including cost and performance”, said Conlan.
When we asked Alex about the concern we often hear at tradeshows: "If one of those tires go down, I’m stuck and I can’t limp into the next station like I can if I’m running duals.” He said Prime and their drivers value the investment they have in their tires and vehicles. "Why would you risk ruining the other dual or damaging the truck by continuing to roll? Whether it’s a wide base tire or dual application, we stop until we can get the tire repaired or replaced. On top of that, our drivers don’t want to risk a 30-point hit on their CSA score, especially since that stays with them if they move to another company.”
It was also good to hear about Prime’s belief in proper inflation through automated inflation systems and tire pressure monitoring systems (TPMS). They currently run inflation systems on 100% of their trailers and TPMS on all their trucks. We asked if it was a difficult decision for Prime to invest in these systems and Alex’s response really reflects Prime’s view that their tires are investment to be cared for: "Look, when you do a yard check and 20% of the tires in the yard are under-inflated it’s a pretty easy calculation to look at the improved return on investment your going to get in terms of fuel savings, better tread wear and casing life if you keep your tires properly inflated.”
We couldn’t have said it better ourselves.